1. Field of the Invention
The present invention relates to home networking. More particularly, the present invention relates to synchronizing content between a content directory service and a control point in a home networking environment.
2. Description of the Related Art
Universal Plug and Play (UPnP) is a distributed, open networking architecture that allows devices to connect seamlessly and to simplify the implementation of networks in the home (data sharing, communications, and entertainment) and corporate environments. UPnP achieves this by defining and publishing UPnP device control protocols built upon open, Internet-based communication standards.
UPnP has grown in popularity of late in part due to the rise in popularity of media servers. Media servers are small computers that store multiple types of content (e.g., photos, music, videos, etc.). The content may then be streamed from a media server to one or more control points (e.g., iPod, television set, etc.).
As an example, a “Media Server” device might contain a significant portion of the homeowner's audio, video, and still-image library. In order for the homeowner to enjoy this content, the homeowner must be able to browse the objects stored on the Media Server, select a specific one, and cause it to be “played” on an appropriate rendering device.
For maximum convenience, it is highly desirable to allow the homeowner to initiate these operations from a variety of User Interface (UI) devices. In most cases, these UI devices will either be a UI built into the rendering device, or a stand-alone UI device such as a wireless PDA or tablet. In any case, it is unlikely that the homeowner will interact directly with the device containing the content (i.e. the homeowner won't have to walk over to the server device). In order to enable this capability, the service device needs to provide a uniform mechanism for UI devices to browse the content on the server and to obtain detailed information about individual content objects. This is the purpose of the Content Directory Service (CDS).
The Content Directory Service additionally provides a lookup/storage service that allows clients (e.g. UI devices) to locate (and possibly store) individual objects (e.g. songs, movies, pictures, etc) that the (server) device is capable of providing. For example, this service can be used to enumerate a list of songs stored on an MP3 player, a list of still-images comprising various slide-shows, a list of movies stored in a DVD-Jukebox, a list of TV shows currently being broadcast, a list of songs stored in a CD-Jukebox, a list of programs stored on a PVR (Personal Video Recorder) device, etc. Nearly any type of content can be enumerated via this Content Directory service. For those devices that contain multiple types of content (e.g. MP3, MPEG2, JPEG, etc), a single instance of the Content Directory Service can be used to enumerate all objects, regardless of their type.